Re: [PATCH] ppc/pnv: Remove user-created PHB{3,4,5} devices

["Cédric Le Goater" <clg@kaod.org>]

On 3/14/22 15:16, Frederic Barrat wrote:
> 
> 
> On 14/03/2022 14:05, Cédric Le Goater wrote:
>> On a real system with POWER{8,9,10} processors, PHBs are sub-units of
>> the processor, they can be deactivated by firmware but not plugged in
>> or out like a PCI adapter on a slot. Nevertheless, having user-created
>> PHBs in QEMU seemed to be a good idea for testing purposes :
>>
>>   1. having a limited set of PHBs speedups boot time.
>>   2. it is useful to be able to mimic a partially broken topology you
>>      some time have to deal with during bring-up.
>>
>> PowerNV is also used for distro install tests and having libvirt
>> support eases these tasks. libvirt prefers to run the machine with
>> -nodefaults to be sure not to drag unexpected devices which would need
>> to be defined in the domain file without being specified on the QEMU
>> command line. For this reason :
>>
>>   3. -nodefaults should not include default PHBs
>>
>> User-created PHB{3,4,5} devices satisfied all these needs but reality
>> proves to be a bit more complex, internally when modeling such
>> devices, and externally when dealing with the user interface.
>>
>> Req 1. and 2. can be simply addressed differently with a machine option:
>> "phb-mask=<uint>", which QEMU would use to enable/disable PHB device
>> nodes when creating the device tree.
>>
>> For Req 3., we need to make sure we are taking the right approach. It
>> seems that we should expose a new type of user-created PHB device, a
>> generic virtualized one, that libvirt would use and not one depending
>> on the processor revision. This needs more thinking.
>>
>> For now, remove user-created PHB{3,4,5} devices. All the cleanups we
>> did are not lost and they will be useful for the next steps.
>>
>> Fixes: 5bc67b052b51 ("ppc/pnv: Introduce user creatable pnv-phb4 devices")
>> Fixes: 1f6a88fffc75 ("ppc/pnv: Introduce support for user created PHB3 devices")
>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>> ---
> 
> So with this patch, -nodefaults has basically no effect on the PHBs and root ports creation. They are always there. It makes sense, since we are removing the capability to add a subset of them.

yes.

Could you please torture a bit the command line with this patch ?
or use the ppc-7.0 branch :

  https://gitlab.com/legoater/qemu/-/commit/34fb665f065f26599365f413ebe83cb47a0e5275

Thanks,

C.

> Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
>
> 
> 
>>   include/hw/ppc/pnv.h       |  1 -
>>   hw/pci-host/pnv_phb3.c     | 33 ++------------------
>>   hw/pci-host/pnv_phb4.c     | 62 ++------------------------------------
>>   hw/pci-host/pnv_phb4_pec.c |  7 ++---
>>   hw/ppc/pnv.c               | 25 +--------------
>>   5 files changed, 10 insertions(+), 118 deletions(-)
>>
>> diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
>> index 1e34ddd502d8..86cb7d7f971b 100644
>> --- a/include/hw/ppc/pnv.h
>> +++ b/include/hw/ppc/pnv.h
>> @@ -190,7 +190,6 @@ DECLARE_INSTANCE_CHECKER(PnvChip, PNV_CHIP_POWER10,
>>   PowerPCCPU *pnv_chip_find_cpu(PnvChip *chip, uint32_t pir);
>>   void pnv_phb_attach_root_port(PCIHostState *pci, const char *name);
>> -void pnv_chip_parent_fixup(PnvChip *chip, Object *obj, int index);
>>   #define TYPE_PNV_MACHINE       MACHINE_TYPE_NAME("powernv")
>>   typedef struct PnvMachineClass PnvMachineClass;
>> diff --git a/hw/pci-host/pnv_phb3.c b/hw/pci-host/pnv_phb3.c
>> index aafd46b635e8..ac801ac83582 100644
>> --- a/hw/pci-host/pnv_phb3.c
>> +++ b/hw/pci-host/pnv_phb3.c
>> @@ -994,30 +994,6 @@ static void pnv_phb3_realize(DeviceState *dev, Error **errp)
>>       PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
>>       int i;
>> -    /* User created devices */
>> -    if (!phb->chip) {
>> -        Error *local_err = NULL;
>> -        BusState *s;
>> -
>> -        phb->chip = pnv_get_chip(pnv, phb->chip_id);
>> -        if (!phb->chip) {
>> -            error_setg(errp, "invalid chip id: %d", phb->chip_id);
>> -            return;
>> -        }
>> -
>> -        /*
>> -         * Reparent user created devices to the chip to build
>> -         * correctly the device tree.
>> -         */
>> -        pnv_chip_parent_fixup(phb->chip, OBJECT(phb), phb->phb_id);
>> -
>> -        s = qdev_get_parent_bus(DEVICE(phb->chip));
>> -        if (!qdev_set_parent_bus(DEVICE(phb), s, &local_err)) {
>> -            error_propagate(errp, local_err);
>> -            return;
>> -        }
>> -    }
>> -
>>       if (phb->phb_id >= PNV_CHIP_GET_CLASS(phb->chip)->num_phbs) {
>>           error_setg(errp, "invalid PHB index: %d", phb->phb_id);
>>           return;
>> @@ -1077,10 +1053,7 @@ static void pnv_phb3_realize(DeviceState *dev, Error **errp)
>>       pci_setup_iommu(pci->bus, pnv_phb3_dma_iommu, phb);
>> -    if (defaults_enabled()) {
>> -        pnv_phb_attach_root_port(PCI_HOST_BRIDGE(phb),
>> -                                 TYPE_PNV_PHB3_ROOT_PORT);
>> -    }
>> +    pnv_phb_attach_root_port(PCI_HOST_BRIDGE(phb), TYPE_PNV_PHB3_ROOT_PORT);
>>   }
>>   void pnv_phb3_update_regions(PnvPHB3 *phb)
>> @@ -1131,7 +1104,7 @@ static void pnv_phb3_class_init(ObjectClass *klass, void *data)
>>       dc->realize = pnv_phb3_realize;
>>       device_class_set_props(dc, pnv_phb3_properties);
>>       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>> -    dc->user_creatable = true;
>> +    dc->user_creatable = false;
>>   }
>>   static const TypeInfo pnv_phb3_type_info = {
>> @@ -1201,7 +1174,7 @@ static void pnv_phb3_root_port_class_init(ObjectClass *klass, void *data)
>>       device_class_set_parent_realize(dc, pnv_phb3_root_port_realize,
>>                                       &rpc->parent_realize);
>> -    dc->user_creatable = true;
>> +    dc->user_creatable = false;
>>       k->vendor_id = PCI_VENDOR_ID_IBM;
>>       k->device_id = 0x03dc;
>> diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c
>> index d1a911f988b7..b30176209303 100644
>> --- a/hw/pci-host/pnv_phb4.c
>> +++ b/hw/pci-host/pnv_phb4.c
>> @@ -1545,70 +1545,14 @@ static void pnv_phb4_instance_init(Object *obj)
>>       object_initialize_child(obj, "source", &phb->xsrc, TYPE_XIVE_SOURCE);
>>   }
>> -static PnvPhb4PecState *pnv_phb4_get_pec(PnvChip *chip, PnvPHB4 *phb,
>> -                                         Error **errp)
>> -{
>> -    Pnv9Chip *chip9 = PNV9_CHIP(chip);
>> -    int chip_id = phb->chip_id;
>> -    int index = phb->phb_id;
>> -    int i, j;
>> -
>> -    for (i = 0; i < chip->num_pecs; i++) {
>> -        /*
>> -         * For each PEC, check the amount of phbs it supports
>> -         * and see if the given phb4 index matches an index.
>> -         */
>> -        PnvPhb4PecState *pec = &chip9->pecs[i];
>> -
>> -        for (j = 0; j < pec->num_phbs; j++) {
>> -            if (index == pnv_phb4_pec_get_phb_id(pec, j)) {
>> -                return pec;
>> -            }
>> -        }
>> -    }
>> -
>> -    error_setg(errp,
>> -               "pnv-phb4 chip-id %d index %d didn't match any existing PEC",
>> -               chip_id, index);
>> -
>> -    return NULL;
>> -}
>> -
>>   static void pnv_phb4_realize(DeviceState *dev, Error **errp)
>>   {
>>       PnvPHB4 *phb = PNV_PHB4(dev);
>> -    PnvMachineState *pnv = PNV_MACHINE(qdev_get_machine());
>> -    PnvChip *chip = pnv_get_chip(pnv, phb->chip_id);
>>       PCIHostState *pci = PCI_HOST_BRIDGE(dev);
>>       XiveSource *xsrc = &phb->xsrc;
>> -    BusState *s;
>> -    Error *local_err = NULL;
>>       int nr_irqs;
>>       char name[32];
>> -    if (!chip) {
>> -        error_setg(errp, "invalid chip id: %d", phb->chip_id);
>> -        return;
>> -    }
>> -
>> -    /* User created PHBs need to be assigned to a PEC */
>> -    if (!phb->pec) {
>> -        phb->pec = pnv_phb4_get_pec(chip, phb, &local_err);
>> -        if (local_err) {
>> -            error_propagate(errp, local_err);
>> -            return;
>> -        }
>> -    }
>> -
>> -    /* Reparent the PHB to the chip to build the device tree */
>> -    pnv_chip_parent_fixup(chip, OBJECT(phb), phb->phb_id);
>> -
>> -    s = qdev_get_parent_bus(DEVICE(chip));
>> -    if (!qdev_set_parent_bus(DEVICE(phb), s, &local_err)) {
>> -        error_propagate(errp, local_err);
>> -        return;
>> -    }
>> -
>>       /* Set the "big_phb" flag */
>>       phb->big_phb = phb->phb_id == 0 || phb->phb_id == 3;
>> @@ -1766,7 +1710,7 @@ static void pnv_phb4_class_init(ObjectClass *klass, void *data)
>>       dc->realize         = pnv_phb4_realize;
>>       device_class_set_props(dc, pnv_phb4_properties);
>>       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>> -    dc->user_creatable  = true;
>> +    dc->user_creatable  = false;
>>       xfc->notify         = pnv_phb4_xive_notify;
>>   }
>> @@ -1864,7 +1808,7 @@ static void pnv_phb4_root_port_class_init(ObjectClass *klass, void *data)
>>       PCIERootPortClass *rpc = PCIE_ROOT_PORT_CLASS(klass);
>>       dc->desc     = "IBM PHB4 PCIE Root Port";
>> -    dc->user_creatable = true;
>> +    dc->user_creatable = false;
>>       device_class_set_parent_realize(dc, pnv_phb4_root_port_realize,
>>                                       &rpc->parent_realize);
>> @@ -1894,7 +1838,7 @@ static void pnv_phb5_root_port_class_init(ObjectClass *klass, void *data)
>>       PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>>       dc->desc     = "IBM PHB5 PCIE Root Port";
>> -    dc->user_creatable = true;
>> +    dc->user_creatable = false;
>>       k->vendor_id = PCI_VENDOR_ID_IBM;
>>       k->device_id = PNV_PHB5_DEVICE_ID;
>> diff --git a/hw/pci-host/pnv_phb4_pec.c b/hw/pci-host/pnv_phb4_pec.c
>> index a0dfa77c8432..6f1121a9489a 100644
>> --- a/hw/pci-host/pnv_phb4_pec.c
>> +++ b/hw/pci-host/pnv_phb4_pec.c
>> @@ -120,6 +120,7 @@ static void pnv_pec_default_phb_realize(PnvPhb4PecState *pec,
>>       PnvPHB4 *phb = PNV_PHB4(qdev_new(pecc->phb_type));
>>       int phb_id = pnv_phb4_pec_get_phb_id(pec, stack_no);
>> +    object_property_add_child(OBJECT(pec), "phb[*]", OBJECT(phb));
>>       object_property_set_link(OBJECT(phb), "pec", OBJECT(pec),
>>                                &error_abort);
>>       object_property_set_int(OBJECT(phb), "chip-id", pec->chip_id,
>> @@ -150,10 +151,8 @@ static void pnv_pec_realize(DeviceState *dev, Error **errp)
>>       pec->num_phbs = pecc->num_phbs[pec->index];
>>       /* Create PHBs if running with defaults */
>> -    if (defaults_enabled()) {
>> -        for (i = 0; i < pec->num_phbs; i++) {
>> -            pnv_pec_default_phb_realize(pec, i, errp);
>> -        }
>> +    for (i = 0; i < pec->num_phbs; i++) {
>> +        pnv_pec_default_phb_realize(pec, i, errp);
>>       }
>>       /* Initialize the XSCOM regions for the PEC registers */
>> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
>> index e7cd8b62ca43..00f57c9678e6 100644
>> --- a/hw/ppc/pnv.c
>> +++ b/hw/ppc/pnv.c
>> @@ -1141,9 +1141,7 @@ static void pnv_chip_power8_instance_init(Object *obj)
>>       object_initialize_child(obj, "homer", &chip8->homer, TYPE_PNV8_HOMER);
>> -    if (defaults_enabled()) {
>> -        chip8->num_phbs = pcc->num_phbs;
>> -    }
>> +    chip8->num_phbs = pcc->num_phbs;
>>       for (i = 0; i < chip8->num_phbs; i++) {
>>           object_initialize_child(obj, "phb[*]", &chip8->phbs[i], TYPE_PNV_PHB3);
>> @@ -1974,23 +1972,6 @@ static ICSState *pnv_ics_get(XICSFabric *xi, int irq)
>>       return NULL;
>>   }
>> -void pnv_chip_parent_fixup(PnvChip *chip, Object *obj, int index)
>> -{
>> -    Object *parent = OBJECT(chip);
>> -    g_autofree char *default_id =
>> -        g_strdup_printf("%s[%d]", object_get_typename(obj), index);
>> -
>> -    if (obj->parent == parent) {
>> -        return;
>> -    }
>> -
>> -    object_ref(obj);
>> -    object_unparent(obj);
>> -    object_property_add_child(
>> -        parent, DEVICE(obj)->id ? DEVICE(obj)->id : default_id, obj);
>> -    object_unref(obj);
>> -}
>> -
>>   PnvChip *pnv_get_chip(PnvMachineState *pnv, uint32_t chip_id)
>>   {
>>       int i;
>> @@ -2130,8 +2111,6 @@ static void pnv_machine_power8_class_init(ObjectClass *oc, void *data)
>>       pmc->compat = compat;
>>       pmc->compat_size = sizeof(compat);
>> -
>> -    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB3);
>>   }
>>   static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
>> @@ -2150,8 +2129,6 @@ static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
>>       pmc->compat = compat;
>>       pmc->compat_size = sizeof(compat);
>>       pmc->dt_power_mgt = pnv_dt_power_mgt;
>> -
>> -    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB4);
>>   }
>>   static void pnv_machine_power10_class_init(ObjectClass *oc, void *data)